Overload release coupling



A E 2, was v G. FAST 2,038,896

OVERLOAD RELEASE COUPLING Filed June 12, 1931 3 Sheets-Sheet l INVENTOR BY ATTORNEY EZQAYL' mi?! 28, 3%. e. FAST OVERLOAD RELEASE COUPLING 3 Sheet sSheet 2 k iluiili) Filed June 12, 1931 I INVENTOR BY ATTORNEY W 2, ca. FAST Q 2,38,

- OVERLOAD RELEASE COUPLING Filed June 12, 1931 5 Sheets-Sheet 3 ATTOR Y Patented Apr. 28, 1936 STATES PATENT OFFIQE OVERLOAD RELEASE COUPLING Gustave Fast, Annapolis, .Md., assignor to Gustave Fast Engineering Corporation, Annapolis, Md., a corporation of Maryland Application June 12, 1931, Serial No. 543,866.

Claims. (01. 192.-56)

This invention relates tocoupling devices ing connected either directly or through suitable adapted to transmit a predetermined amount of means to a power driving means, and the other torque between a pair of rotatable members and being connected, for example, to a pump or the which will yield upon the placing of an excessive like. On the shaft in there may be mounted a 5 load upon the driven member so as to prevent hub l2 which is keyed to the shaft for rotation serious injury to any of the parts of the machine therewith. This hub may be provided along its embodying the coupling. periphery with a series of teeth or spline pro- It has been a primary object of the present injections l3 adapted to mesh or cooperate with vention to provide a coupling which will be reinternal teeth orprojections 14 carried by a sleeve leased upon the application of a predetermined or housing member l5. The latter may be con- 10 overload without the use of any shear pins or nected to a second sleeve or housing member It similar breakable parts which require replaceby means of a series of bolts l'i passed through ment uponthe release of the coupling. The inflanges integral with thesleeves.

vention further has in view the elimination of Through the means which will presently be 15 all of the objectionable features of the shear pin described, the member t6 has a normal driving 15,

type of coupling and the production of a unit connection with a hub l8 mounted on and keyed which may be effectively provided with any deto the shaft II. The driving connection between sired overload factor. The construction contemthese parts, however, is such that it will be replated is simple, compact and reliable in its leased upon the application of an excessive load action and after release may very readily be to the shaft H. A series of teeth or projections 20,

reset to permit the transmission of the desired l9' carried by the periphery of the hub l8 are torque. adapted to cooperate with corresponding inter- Other features and advantages of the invennal teeth or projections 26 carried by an annular tion will be set forth in the claims and in the member 2|. The latter in its outer surface is detailed description of an illustrative embodiprovided with a notch or indentation 22 having 25,

ment of the same which will now be given in sloping sides 23 and adaptedto receive a projecconjunction with the accompanying drawings in tion 24 which is integral with a rotatable pin or which: stud 25. This stud is' suitably journalled within Figure 1 is a side elevatio-nal' View, partly in openings provided partly within the member I6 section, of a coupling embodying the overload and partly within a plate or closure member 26 30 release mechanism of the present invention. bolted to a flattened portion of the'periphery of Figure 2 is a front elevation, partly in section, member l6 adjacent its outer end. Near its left taken along the line 2-2 of Figure l, of the imend, as viewed in Figure 1, the stud 25 is pro- P d p g. vided with a segmental projection 21, whose form Figure 3 is a detail, sectional view taken along is best illustrated in Figures 2 and 4'. This pro- 35' the line 3--3 of Figure 1. jection is provided with a notch 28 in its outer Figure 4 is a detail view showing certain of the surface, the sides of the notch being inclined at parts Of Fi r 2 n a hifted position. a suitable angle to a line extending radially Fi r 5 s a lon i u in l i n l v w toward the axis of the stud. A projection 29 40 through portion of a modified fhlm 0f COIIDIiIIg. having correspondingly tapered sides and carried Figure 6 is a transverse sectional view of a deby or integral with a spring member 3!], which ta l taken along the line 5- o Figure 5 in the may conveniently be in the form of a flat leaf di ec on i d c d by the w. spring, is adapted to cooperate with the notch Figure 7 is a- V W m ar to Figure 6 but taken 28. It will be apparent that due to the co-action 45 in the Opp direction a g line 0f of the projection 29 with the notch 28, the pro- 45 ure 5. jection 21, and hence the stud 25, will normally Figure 8 illustrates the parts shown in Figure 7 be re nted from rotation,

n Shifted D Through the cooperation of the projection 24 F r 9 s a sectional vi w taken along the on the stud with the notch 22 in the member 2| line o Figure and the latter will then be constrained to move with 50 Fi r 0 isav w m l o Fi re 5i11u r the sleeve or housing member It so that the in the parts Shifted as n Figure 8. torque transmitted to the latter will in turn be Referring now to Figures 1 to.4 of the drawtransmitted to the hub l8 and shaft ll. Howings, there is shown a pair of aligned shafts I0 ever, should the shaft ll meet with undue reand II which are to be coupled together, one besistance to rotation, there will be a tendency for the annular member 2| to act upon the projection 24 of the stud 25 and attempt to rotate the latter within its bearings. If this turning force is sufficiently great, the side of the notch 28 in the projection 27 will cause the projection 29 of the spring member 30 to be cammed upwardly,

thereby releasing the stud for partial rotation. When it has rotated through an angle of about 60 degrees, the projection 24 will have been completely disengaged from the member 2| and the driving connection between this member and the sleeve IE will have been broken. Rotation of the stud may be limited, if desired, by an extension 3| formed on the projection 21 and adapted to cooperate with the projection 29 of the spring 30 after the stud has rotated sufficiently to release the coupling. The parts will remain in released position during continued rotation of the shaft l0 and until they are readjusted to bring the necessary projections and notches into alignment.

In order to prevent excessive wear of the cooperating faces of either member IE or the an nular member 2| during the relative movement of these parts after the coupling has been released, a liner 32 of any suitable bearing material, such as bronze or Babbitt metal, may be provided between these surfaces, or the member 2| may be made of bronze and no lining such as '32 used.

It will be desirable to have the coupling partially filled with a suitable lubricant and for the purpose of retaining the same within the housing formed by the sleeve members l5 and I6, a closure element 33 of suitable construction is provided at the left end of the member l8, as best shown in Figure 1. Removable plates 34, bolted to the sleeve l6 and cover 33, may be provided in line with the stud 25 to permit ready access to the latter. At the opposite end of the coupling a closure 35 may be provided and bolted, or fastened in any other suitable way, to the sleeve member IS. The radially inward facing surface 36 of the cover 35 which cooperates with 'a portion of the hub I2 is preferably rounded slightly so as to permit a certain amount of angular movement between the shaft l0 and the sleeve member 5. A similar limited, angular movement is permitted between the shaft and the sleeve I6 by a slight rounding of the ends of the projections IS on the hub l8 which, it will be noted, is at a point radially in line with the projection 24 of the stud 25. In the event of a release of the coupling the lubricant in the housing will work its way between the relatively sliding surfaces of the members 2| and 32 to prevent undue wear.

After the coupling has been released, in the manner indicated, it may be restored to its normal coupling condition by properly aligning and meshing the notch 22 in the ring 2| with the projection 24. When these parts are brought into proper relation, the projection 29 of the spring 38 will drop into the notch 28 of the projection 21. It will be noted that the projection 21 is provided with symmetrical portions on the two sides of the notch 28 and that the balance of the mechanism is similarly symmetrically arranged so that the coupling may be released during rotation of the parts in either direction.

The construction illustrated in Figures 1 to 4 has the advantage of providing only a single driving projection between the sleeve or housing member and the corresponding hub. This eliminates the necessity of insuring the simultaneous action of a series of projections. It is to be noted in this connection that the radial distance from the axis of the stud 25 (Fig. 3) to the point at which the force is applied to the projection 24 by the side of the notch 22 is considerably shorter than the distance from this point of engagement to the center of the shaft Furthermore, the first mentioned distance is less than that from the center of the stud to the point of contact between the spring projection 29 and the side wall of the notch 28. In this way a considerable mechanical advantage is derived in favor of the projection 29 so that the projection 24 is enabled to transmit a force to the shaft II of considerable magnitude without causing release of the coupling. By an appropriate variation of these distances, as well as by a variation in the slope of the sides of the notch 28 and the strength of the spring 30, the load at which the coupling will be released may be readily varied to suit the particular requirements.

In Figures 5 to 10, inclusive, there is shown a further modification of the invention in which the parts, which are separated by a camming action against a resilient force to release the coupling under conditions of excessive load, are moved axially with respect to the coupled shafts rather than radially as in the previously described embodiments. The two shafts to be coupled are designated 61 and 68, respectively, in Figure 5 and on each there is secured a hub or similar member for rotation therewith. For example, a member 69 may be keyed to the shaft 61 while a member 18 may be keyed to the shaft 68. An annular extension H of the member 10 surrounds the member 69 and in conjunction with the plate or closure 12, which is fastened by bolts 13, or the like, to the member l8, it may serve to completely enclose the member 69. Within the annular extension N there may be formed one or more cylindrical pockets 14 having their axes parallel to the common axis of the coupled shafts. Each pocket 14 may be provided with a substantially cylindrical interior surface 15 which receives and cooperates with a corresponding surface on the periphery of a quill shaft 16. The latter carries an elongated tooth-like projection 11 which is adapted to cooperate with a groove or notch 18 formed in the exterior surface of the member 69. It will be apparent that so long as the projection 11 remains in engagement or mesh with the groove 18, a driving relation will exist between the members 69 and 10.

For the purpose of holding the projection TI and notch 18 in properly meshed relation, as shown in Figure 7, a suitable resilient detent mechanism is provided. This may include the provision of face cams comprising axially extending projections 19 formed preferably at both ends of the quill shaft 16 with alternate depressions between the projections. Cooperating with these face cams there may be provided complementary face cams formed by depressions BI and projections 82 carried by a pair of disclike members 83. These members may be permitted a slight axial, sliding movement but are held against rotation within the pockets 14 by means of projections at opposite sides cooperating with guide grooves 85 formed in the wall of the cylindrical pocket 14 and in the extension of this wall formed in the cover element 12. The quill shaft 16 and the two disc-like members 83 are slidably carried by a rod 86 which at one end is preferably threaded and adapted to reoff along the threadedr portionv of the rod 86" to ceive a nut 81 and at its opposite. end isprovided with an enlarged head 88 corresponding in form. to the elements 83... Projections 89, simi' lar to the projections 84', extend laterally from the head 88 and are adapted to cooperate with.

the grooves 85 to prevent rotation of the-rod.

Between the inner element 83 and the head. 88 there may be provided any suitable form. of spring or similar resilient means. In the drawings, there is shown a type of resilient means,

including sets of outer, elastic or resilient rings 98 and inner, elastic or resilient rings 9|. These rings, as shown in Figures 5, 9 and 10, are provided with inclined, cooperating faces which are at a relatively small angle, preferably between and 30 to the axis of the rings. It will be apparent that relative axial movement of the rings will be yieldingly resisted. Any axial movement which may take place between. the rings due to the relative movement of the inner disc 83 toward the head 88 will cause the inclined, cooperating surfaces of the rings 98 to produce a Wedging action upon the inner rings 9| so as to compress the latter. The inner rings. in turn will tend to produce an outward wedging action upon the rings 90, tending to expand these. Due to the stresses and strains which are thus set up in the two sets of rings, energy will be.

stored in the same and this energy will be effective to provide quick release of the rings when the element 83 and head 88 are again separated. It will be apparent that the operation of the rings is such that there is provided both a resilient opposition to the movement of the element 83 and head 88 toward each other and a frictional resistance to this relative movement due to the sliding of the camming or wedging surfaces of the rings as they are shifted axially. Both sets of rings 90 and 9| are complete, unbroken, annular members formed preferably of material having high elastic or resilient properties. The rings 98 should be formed of material which has high elasticity or resilience under tensile or expanding forces, while the rings 8| should have high elasticity or resilience under compressional forces.

The operation of this form of the invention will be apparent. Under normal conditions the torque will be transmitted between the shafts 87 and 68 through the inter-engagement of the projection T! with the groove 18. However, when an excessive torque is encountered, the quill shaft 18 may be rotated slightly from the position shown in Figure 7 to that shown in Figure 8. In rotating the quill shaft about the rod 86, the projections 19 of the face cams will force the two elements 83 apart. The outer element 83 will, through cooperation with the nut 81, shift the rod 88 to the left, thus drawing the head 88 toward the inner element 83. This will result in the relative, axial movement of the rings 98 and 9!, which is resisted, as previously explained, by the resilience of the rings, as Well as by the friction between the cooperating, sliding faces. When the quill shaft has been shifted to the position shown in Figure 10, it will be held in that position by the cooperation of the end faces of the projections 19 and 82, as shown in Figure 10. This will permit free or independent rotation of the two shafts until the parts are re-set.

In re-setting the parts it is simply necessary to bring the groove 18 into mesh with the projection H, the quill shaft being rotated, in so doing, into the position shown in Figure '7. At this time, if desired, the nut 81 may be backed release the pressure between the rings 98 and 9|.

The load under which. the coupling will be automatically released, in the. manner explained, may be varied: in a number ofways. In the initial construction of the coupling the torque which may be:v transmitted through the quill shaft may be varied to suit. the particular requirementsby adopting a. proper ratio between. the radii from the axis of the. quill shaft to the center of pressure of the projection H and from the axis of the" shaft. 61 to the center of pressure of the groove. 18. The load at. which release will be automatically effected. may also be made to suit particular requirements. by proper inclination of the camming edges of the. projections 19 and 82. Variation. in the permissible torque which may be transmitted through any given. coupling after construction. may be. effected at. will by tightening or loosening the nut 81. It will be apparent thatzif. this nut-is tightened to provide a greater initial tension upon the spring formed by the rings 98 and 9 1:, the load under which release would bezautomatically effected will be increased.

In order to permit proper lubrication of all of the-.partsat. a time when relative movement takes place between them, the cylindrical pockets 14 are preferably provided at one end with a removable cover 92 and. at the: opposite end with a cover-plate 93. These. may be secured in any suitable way, as by means of the bolts shown. Oil or other lubricant may thus be retained within the housing formed by the coupling.

While this form of the invention has been described with reference to only a single quill shaft 16, it will be understood that two or more of these shafts may be provided if desired to enable the transmission of .a greater torque through a construction of given diameter. In the illustrated form of this modification of the invention the member 18 is shown as provided with an integral annular extension surrounding the member 69; however, this part of the construction may, if desired, be made similar to that of the form shown in Figure 1. In that event the cylindrical pocket 14 will be carried by a separate sleeve member which will surround the hub elements keyed to the alined shafts and will be splined to these hub elements.

While several admirable embodiments of the invention have been disclosed in considerable detail, it will be understood that numerous variations, in addition to those already mentioned, may be adopted without departing from the general spirit and scope of the invention.

What I claim is:

1. An overload release coupling for a pair of rotatable shafts which comprises a member continuously connected with one of said shafts, a second member continuously connected with the other of said shafts, a rotatable stud carried by one of said members, a projection integral with said stud intermediate its ends adapted to engage a recess in the other of said members, and yielding means comprising a pair of spring urged elements engaging the ends of said stud for normally preventing rotation of said stud to enable positive transmission of a torque between said members, said means being adapted to yield to disconnect said members upon receipt of an excessive load.

2. An overload release coupling for a pair of rotatable shafts comprising a member connected for rotation with each shaft, inter-engaging means carried by said members adapted to positively transmit a torque between the same, said means including a rockable stud carried by one of said members and resilient means comprising a plurality of axially shiftable unbroken rings adapted to oppose disengagement of said interengaging means.

3. An overload release coupling for a pair of rotatable shafts which comprises a member connected for rotation with each shaft, an element pivotally carried by one of said members upon a pivot parallel with said shafts and having a part adapted to engage the other member, means for retaining said element in engagement with the other member to effect a positive connection between the members comprising resilient means having its axis parallel to that of said shafts, and camming surfaces on said element at an angle of less than 45 degrees to the axis of its pivot for overcoming said retaining means when a predetermined torque is exceeded.

4. An overload release coupling for a pair of elements to be coupled which comprises a member continuously connected with one of said elements, a second member continuously connected with the other of said elements, one of said members having a notch formed therein, a stud parallel with the axes of said elements movably carried by the other of said members, said stud having an inwardly extending integral projection adapted to engage said notch and provide a positive connection between said elements, resilient means cooperating with said stud at a point further from the axis thereof and nearer the axis of said elements than the end of said projection for normally holding said notch and projection in engagement, and cam means eifective upon the application of a predetermined load to said coupling for opposing said resilient means and releasing the coupling.

5. An overload release coupling between driving and driven members which comprises an elongated stud rockably mounted in one of said members adjacent the periphery thereof, a projection extending radially inwardly from said stud and arranged to engage a notch in the other of said members to positively connect said members for rotation in unison in either direction, steep, substantially flat cam surfaces formed on said stud adjacent one end, at least a part of said surfaces being between the axis of the stud and the axis of said members, and a spring urged projection having corresponding cam faces cooperating with said cam surfaces, said surfaces and faces being arranged at such an angle as to act at a mechanical advantage in resisting turning of said stud, said spring urged projection being adapted to yield under the action of said cam surfaces to permit rocking of said stud when a predetermined load is exceeded.

GUSTAVE FAST. 

